In recent years, in order to introduce natural energy power generation, large scaling of distributed-type power supplies, such as solar light power generation facilities and wind power generation facilities, and battery systems for power fluctuation suppression or for peak shifting are advancing. Such distributed-type power supplies and battery systems are interconnected to a power system of, for example, an electricity power company via system interconnecting facilities.
System interconnecting facilities are facilities for electric power interchange between the distributed-type power supply and the battery system, and the power system, and include equipment, such as a transformer, a switch, and a power converter. The system interconnecting facilities interchanges power by mainly discharging power to the power system when connected to the distributed-type power supplies, and charges and discharges power between the power system when connected to the battery system.